The present invention relates to polymorphic forms of (S)-1-cyanobutan-2-yl (S)-1-(3-(3-(3-methoxy-4-(oxazol-5-yl)phenyl)ureido)phenyl)ethylcarbamate having the structure below (hereinafter “Compound 1”):

The present invention also relates to processes to prepare polymorphic forms of Compound 1.
Compound 1 is a potent IMPDH inhibitor useful in treating IMPDH-mediated diseases. Compound 1, compositions thereof, and methods therewith are disclosed in U.S. Pat. No. 6,498,178 ((hereinafter “the '178 patent”), the entire disclosure whereof is incorporated herein by reference